Effect of Environmental Acidity on the Formation of a Floating Layer, Morphology, and Optical Properties of Langmuir-schaefer Films of 5,10,15,20-tetrakis[4-(10-carboxydecyloxy)phenyl]porphyrine With Nickel Salts Nanoparticles
Year: 2026
Type: article
Abstract: This work is devoted to a systematic investigation of the influence of aqueous subphase acidity and the presence of nickel ions on the formation of floating layers of 5,10,15,20-tetrakis[4-(10-carboxydecyloxy)phenyl]porphyrin, as well as on the morphology and optical properties of the resulting Langmuir–Schaefer films. Using all-atom molecular dynamics simulations with the OPLS-AA force field and quantum chemical calculations at the DFT level (CAM-B3LYP functional, 6-31G(d,p) basis set), the structural organization of porphyrin molecules at the air/water interface was modeled. The molecular projection areas in the face-on and edge-on orientations were determined, and the predominant J-type aggregation of the macrocycles was established. Experimentally, compression π-A isotherms of floating layers were obtained on subphases with different pH values (5.5–6.5) and nickel chloride concentrations (0.0004–0.004 mol/L). It was shown that the coordination interaction of nickel ions with the carboxyl groups of the carboxyalkoxy substituents leads to a transition of the floating layer from a "condensed" state to a more mobile "liquid-condensed" state, as confirmed by a decrease in the compressibility modulus and a change in the hysteresis loop behavior during compression–decompression cycles. Using a combination of atomic force microscopy, scanning electron microscopy, and polarized optical microscopy, it was found that the introduction of nickel ions into the subphase significantly increases the number and size of island-like three-dimensional aggregates on the film surface, increasing the average roughness from 53.3 to 72.6 nm. At the same time, a decrease in the pH of the medium from 6.5 to 5.5 suppresses uncontrolled aggregation, apparently due to the protonation of the nitrogen atoms of the macrocycle and the weakening of coordination with nickel ions, which leads to the formation of more homogeneous and smooth films. Electronic absorption spectroscopy revealed a bathochromic shift of the Soret band by approximately 20 nm in the films compared to the solution, confirming J-aggregation of the porphyrin molecules. A linear increase in the intensity of the Soret band with an increase in the number of transfers from 1 to 50 was established, indicating high reproducibility of the deposition process. For citation: Maltseva O.V., Nikitin K.S., Dmitrieva O.А., Mamardashvili N.Zh., Zhdanova K.A., Bragina N.A. Effect of environmental acidity on the formation of a floating layer, morphology, and optical properties of langmuir-schaefer films of 5,10,15,20-tetrakis[4-(10-carboxydecyloxy)phenyl]porphyrine with nickel salts nanoparticles. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2026. V. 69. N 10. P. 16-26. DOI: 10.6060/ivkkt.20266910.7142.
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7204950709